Bag seal inspection device

Abstract

A device to inspect a longitudinal heat seal in tubular bag material. The seal is formed by a heated sealing bar ( 14 ). Downstream of the bar ( 14 ) is a heat sensing camera ( 20 ) that sends a signal to a central processing unit ( 21 ). The unit ( 21 ) will then identify any faults in the seal.

The invention claimed is: 
     
       1. A device to inspect a longitudinal heat seal in tubular bag material, the bag material being formed of plastics material having longitudinally extending and overlapping edge portions secured together by the heat seal, the device comprising:
 a bag material drive assembly to engage the tubular bag material to move the tubular bag material along a predetermined path in a predetermined direction; 
 a heat sealing mechanism to engage the longitudinally extending edge portions to heat the edge portions to form said longitudinally extending heat seal, the heat sealing mechanism comprising a heat sealing bar to engage the tubular bag material to form the seal, the bar being supported for movement between an engaging position to engage the bag material to form the seal, and a retracted position at which the heat sealing bar is removed from contact with the tubular bag material, spaced from the engaged position so as not to be engaged with the tubular bag material, and a bar drive assembly operatively associated with the bar to move the bar between the engaged and retracted positions; 
 a camera directed at the heat seal and to provide a signal indicative of the temperature of the heat seal exposed to the camera; and 
 a central processing unit to control the bar drive assembly, wherein the signal is delivered from the camera to the central processing unit so that the central processing unit can control the bar drive assembly based on the temperature of the heat seal. 
 
     
     
       2. The device of  claim 1 , wherein said camera provides a signal indicative of infrared radiation emanating from the seal to thereby provide a signal indicative of the temperature of the seal exposed to the camera. 
     
     
       3. The device of  claim 1 , wherein the camera provides a signal indicative of any temperature gradient transversely across the seal. 
     
     
       4. The device of  claim 1 , wherein the bar drive assembly also generates a signal delivered to the central processing unit to provide an indication of when the bar is engaged with the tubular bag material. 
     
     
       5. The combination of  claim 1 , wherein the bar drive assembly includes a spring urging the bar to the engaged position, and a cylinder to move the bar from the engaged position to the retracted position. 
     
     
       6. The device of  claim 2 , wherein the camera provides a signal indicative of any temperature gradient transversely across the seal. 
     
     
       7. The device of  claim 2 , wherein the bar drive assembly also generates a signal delivered to the central processing unit to provide an indication of when the bar is engaged with the tubular bag material. 
     
     
       8. The combination of  claim 7 , wherein the bar drive assembly includes a spring urging the bar to the engaged position, and a cylinder to move the bar from the engaged position to the retracted position. 
     
     
       9. The device of  claim 3 , wherein the bar drive assembly also generates a signal delivered to the central processing unit to provide an indication of when the bar is engaged with the tubular bag material. 
     
     
       10. The device of  claim 9 , wherein the bar drive assembly includes a spring urging the bar to the engaged position, and a cylinder to move the bar from the engaged position to the retracted position.